超支化聚酯型环氧树脂的合成及表征

用多元酸酐与环氧氯丙烷开环聚合制备了端羟基超支化聚酯,在碱作用下对羟基封端的超支化聚酯进行了闭环反应合成了超支化聚酯型环氧树增,研究了碱及碱的用量对闭环反应的影响,通过DSC考察了超支化聚酯型环氧树脂/邻苯二甲酸酐固化体系的固化行为,计算出固化过程的2个固化反应活化能Ea分别为64 35kJ/mol和91 12kJ/mol,频率因子lnA分别为21 8和26 8。     

超支化聚酯对环氧 -聚酯混合型粉末涂料耐冲击性的改性研究

首先通过准一步法以三羟甲基丙烷（ TMP）为核,以 2,2-二羟甲基丙酸（ DMPA）为 AB2单体,制备了端羟基超支化聚酯（HBPE-OH）。然后采用邻苯二甲酸酐对端羟基超支化聚酯进行端基改性制备了端羧基超支化聚酯（ HBPE-COOH）。研究了上述 2种超支化聚酯对环氧 -聚酯体系固化性能及环氧 -聚酯混合型粉末涂料增韧效果的影响。研究结果表明： HBPE-COOH可使环氧 -聚酯体系的固化程度增大,而 HBPE-OH使环氧 -聚酯体系的固化程度略有降低。由于超支化聚酯分子内存在大量的空腔, 2种 HBPE均可有效提高涂层的耐冲击性能。其中, HBPE-COOH的增韧效果更佳。     

超支化聚酯的合成及改性环氧树脂的研究

以季戊四醇为核,2,2-二羟甲基丙酸为增长单体,对苯甲磺酸为催化剂,合成了超支化聚酯,通过FI-IR图谱对超支化聚酯进行结构表征,证明得到端基为羟基的超支化聚酯。采用超支化聚酯做增韧剂,研究其对环氧/四氢苯酐固化体系的增韧作用,探讨了超支化聚酯的分子量(代数)、超支化聚酯的含量、固化温度等因素对环氧树脂固化体系力学韧性的影响。     

环氧封端的超支化聚酯醚增韧环氧树脂研究

以1,6-二溴己烷为A2单体、3,5-二羟基苯甲酸为CB2单体,通过亲核取代聚合反应合成末端为酚羟基的超支化聚酯醚(HBPEE-OH),再加入等当量的环氧溴丙烷得到末端为环氧基团的超支化聚酯醚(HBPEE-epoxy)。将HBPEE-epoxy添加到环氧/酸酐体系中,采用示差扫描量热仪研究了其对环氧树脂固化过程的影响,发现HBPEE-epoxy的添加会促进体系固化,使起始固化温度前移。对固化物的力学性能及热性能的研究发现当HBPEE-epoxy添加质量分数为4.0%时,固化物的冲击强度、弯曲强度、热分解温度、玻璃化转变温度分别提高了70.66%,19.77%,7.8℃和1.4℃。     

端环氧基超支化聚酯的合成及应用

本文以季戊四醇为心核结构、2,2-二羟甲基丁酸为重复单元、对苯甲磺酸为催化剂,合成了端羟基超支化聚酯;然后,采用环氧氯丙烷对超支化聚酯的端羟基进行环氧官能化,合成端环氧基超支化聚酯,采用GPC、13CNMR及1H-NMR图谱对结构进行表征。采用端环氧基超支化聚酯做增韧剂,研究其对双酚A环氧树脂力学性能的影响,探讨了端环氧基超支化聚酯对环氧树脂固化体系力学性能及韧性的影响。     

环氧树脂/超支化聚合物修饰碳纳米管复合材料的固化反应动力学研究

采用非等温差示扫描量热法（DSC）研究纯环氧树脂（EP）、环氧树脂/碳纳米管复合材料（EP/MWCNTs）、环氧树脂/超支化聚酯修饰碳纳米管复合材料（EP/MWCNTs-H204）和环氧树脂/超支化聚酰胺修饰碳纳米管复合材料（EP/MWCNTs-N103）4种体系的固化动力学。基于Kissinger方法和Ozawa方法计算了各体系反应的活化能。结果表明：经过超支化聚合物修饰的EP/MWCNTs-H204和EP/MWCNTs-N103体系比未经修饰的其余两个体系，具有较低的表观活化能，说明超支化聚合物的引入对环氧树脂复合材料的固化反应具有显著的促进作用。采用Málek方法得出自动催化模型（Sesták-Berggren），利用Sesták-Berggren对各体系进行理论计算，提出了描述固化过程的动力学参数和方程式。理论计算结果与实验结果进行对比相似度较高，说明Sesták-Berggren模型可以很好地描述4种不同环氧树脂体系的固化动力学行为。     

超支化聚酯/聚氨酯体系非等温固化动力学研究

采用非等温差示扫描量热法(DSC)研究了不同代数的超支化聚酯/聚乙二醇型聚氨酯体系的固化反应动力学,采用Kissinger法、Flynn-Wall-Ozawa法、Friedman-Reich-Levi法和Crane公式计算了各体系的表观活化能、反应级数、指前因子以及机理函数等固化反应动力学参数.结果表明,加入6%的第二...     

端羟基聚丁二烯改性氰酸酯体系固化反应动力学

采用示差扫描量热法(DSC)研究了端羟基聚丁二烯(HTPB)改性双酚A型氰酸酯树脂(BADCy)体系的固化反应动力学,根据Arrhenius方程对固化过程动力学参数进行了求解,建立了固化反应动力学模型。结果表明,随着HTPB含量的增大,动态DSC固化反应放热峰向低温方向移动,说明HTPB可以催化固化反应并降低体系的反应温度。纯BADCy和BADCy/15%HTPB体系等温固化符合自催化反应模型。纯BADCy体系以及BADCy/15%HTPB体系的表观反应活化能分别为59.67 kJ/mol、56.91 kJ/mol。     

端异氰酸酯聚醚增韧环氧树脂固化动力学研究

采用差示扫描量热（DSC）技术测定了在芳胺类为固化剂的条件下,增韧环氧体系固化反应过程中的热行为,得出固化反应过程的动力学参数,实验数据表明,以芳胺为固化剂的体系中,固化反应表观活化能及动力学频率因子,反应级数均有明显降低。     

单环氧基活性稀释剂对环氧酸酐体系的作用

考察添加不同量的单环氧基活性稀释剂(H8)对环氧树脂体系固化反应以及介电性能的影响,通过DSC热分析发现,稀释剂添加量越多,DSC曲线放热峰越往高温方向移动,并且峰形变钝,放热过程的△HC基本上随稀释剂用量的增大而减小;由介电损耗-温度谱实验数据显示,随着稀释剂加入量增多,介电损耗值也呈上升趋势,但总体上tanδ还是保持在较低值范围内,155℃tanδ最大值不超过0.04。同时利用DSC跟踪体系固化反应过程,根据Kissinger和Crane方程对该固化反应进行了非等温动力学分析,探讨得出环氧树脂体系的固化动力学参数:固化反应表观活化能△Ea=48.3 kJ/mol,反应级数n=0.89。     

Cure reaction and phase separation behavior of cyanate ester‐cured epoxy/polyphenylene oxide blends

The cure reaction and phase separation mechanism of a cyanate ester‐cured epoxy and its blends with polyphenylene oxide (PPO) were studied. An autocatalytic mechanism was observed for the epoxy and its blends. The reaction rate of the blends was higher than that of the neat epoxy at initial stage; however, the reached conversion decreased with PPO content. FTIR analysis revealed that the cyanate functional group reactions were accelerated by adding PPO and indicated that several coreactions have occurred. This was caused by the reaction of cyanate ester with the PPO reactive chain ends. But at a later stage of cure, the reaction could not progress further due to diffusional limitation of PPO. To understand the relationship between the cure kinetics and phase separation of the blends, the morphology of the blends during cure was examined. When the homogeneous epoxy/PPO blends with low PPO content (10 phr) were cured isothermally, the blends were separated by nucleation and growth (NG) mechanism to form the PPO particle structure. But at high PPO content (30 phr), the phase separation took place via spinodal decomposition (SD). SD is favored near critical concentration and high cure rate system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1139–1145, 2006     

Thermokinetics and chemorheology of the cure reactions of the tetraglycidyl diamino diphenyl methane–diamino diphenyl sulfone epoxy systems

The cure behavior of commercial grade TGDDM–DDS mixtures of compositions ranging from 10 to 100 phr of hardener and the thermal polymerization of the epoxy component are analyzed by means of differential scanning calorimetry. The kinetic parameters and heats of reaction determined in isothermal and dynamic scans suggest that DDS primary amine addition and epoxide etherification dominate the cure reactions. The primary amine epoxide addition is characterized by overall heat of reaction (referred to the weight of the epoxy component) of 255 cal/g and by an activation energy of 16.6 kcal/mol. The corresponding values for the etherification reaction are, respectively, 170 cal/g and 41 kcal/mol. A method of derivation of the epoxide conversion from the heat evolved in DSC thermal scans of these systems is presented. The results are in good agreement with independent IR determinations. The steady shear and oscillatory viscosity measurements and the calorimetric analysis of the isothermal cure at 140°C, 160°C, and 180°C of a TGDDM–DDS mixture containing 35 phr of hardener indicate that gelation is principally governed by the primary amine addition. The gelation limits calculated in isothermal tests by combining the calorimetric analysis and the theory describing the nonlinear copolymerization of the tetrafunctional TGDDM with an essentially difunctional DDS were in good agreement with the values experimentally determined through rheological measurements.     

聚硫橡胶对环氧树脂固化动力学及力学强度的影响

用红外光谱分析了在环氧树脂中加入聚硫橡胶的固化及增韧过程,通过差示扫描量热法研究了增韧体系的反应动力学,探讨了聚硫橡胶用量对固化产物力学强度的影响,并对试样断口形貌进行了扫描电镜观察。结果表明,聚硫橡胶的加入降低了环氧树脂的表观活化能而没有改变反应级数,使得固化反应的总放热量减少、放热过程更加平均。聚硫橡胶对环氧树脂的增韧效果明显,二者通过化学键结合,韧性撕裂的冲击断面形貌验证了这种活性增韧。当聚硫橡胶用量为30份(质量)时,环氧树脂固化物的冲击强度可达到未增韧者的896%。     

聚氨酯改性中温快速固化环氧粘合剂的制备与应用

以聚四氢呋喃醚、异佛尔酮二异氰酸酯、2-乙基咪唑为原料,合成了以2-乙基咪唑封端的聚氨酯,并用于改性环氧树脂E-44.利用傅立叶红外分析仪、示差扫描量热仪、拉伸试验机等手段对其与环氧树脂混合物的凝胶时间、固化温度、解封情况、拉伸剪切强度等性能进行了研究.结果表明,咪唑封端的聚氨酯可以在130℃下较好地解封,每10份E-...     

Improved thermosets obtained from diglycidyl ether of bisphenol A/4,4′‐diaminodiphenylsulfone based on a new epoxy‐terminated hyperbranched polymer

A new hyperbranched polymer (HBP) with a flexible aromatic skeleton and terminal epoxy groups was synthesized to improve the toughness of diglycidyl ether of bisphenol A. The HBP was characterized using nuclear magnetic resonance, Fourier transfer infrared spectroscopy and gel permeation chromatography. The effect of HBP on the thermomechanical and mechanical properties of modified epoxy systems was studied. For evaluating the efficiency of the modified epoxy systems, composite samples using glass fiber cloth were molded and tested. Using dynamic mechanical analysis, a slight reduction in glass transition temperature (T_g) with increasing HBP content was observed. Analysis of fracture surfaces revealed a possible effect of HBP as a toughener and showed no phase separation in the modified resin systems. The results showed that the addition of 15 phr HBP maximized the toughness of the modified resin systems with 215 and 40% increases in impact and flexural strengths, respectively. T_g and heat resistance of cured modified resin systems decreased slightly with an increase in HBP content and, at 15 phr HBP, only a 2.6% decrease in thermomechanical properties was observed. Meanwhile, a molded composite with HBP showed improved mechanical properties and retention rate at 150 °C as compared to that made with neat resin. © 2015 Society of Chemical Industry     

Toughening of epoxy resin systems using low‐viscosity additives

This study has evaluated three low‐viscosity epoxy additives as potential tougheners for two epoxy resin systems. The systems used were a lower‐reactive resin based upon the diglycidyl ether of bisphenol A (DGEBA) and the amine hardener diethyltoluene diamine, while the second epoxy resin was based upon tetraglycidyl methylene dianiline (TGDDM) and a cycloaliphatic diamine hardener. The additives evaluated as potential tougheners were an epoxy‐terminated aliphatic polyester hyperbranched polymer, a carboxy‐terminated butadiene rubber and an aminopropyl‐terminated siloxane. This work has shown that epoxy‐terminated hyperbranched polyesters can be used effectively to toughen the lower cross‐linked epoxy resins, i.e. the DGEBA‐based systems, with the main advantage being that they have minimal effect upon processing parameters such as viscosity and the gel time, while improving the fracture properties by about 54 % at a level of 15 wt% of additive and little effect upon the T_g. This result was attributed to the phase‐separation process producing a multi‐phase particulate morphology able to initiate particle cavitation with little residual epoxy resin dissolved in the continuous epoxy matrix remaining after cure. The rubber additive was found to impart similar levels of toughness improvement but was achieved with a 10–20 °C decrease in the T_g and a 30 % increase in initial viscosity. The siloxane additive was found not to improve toughness at all for the DGEBA‐based resin system due to the poor dispersion within the epoxy matrix. The TGDDM‐based resin systems were found not to be toughened by any of the additives due to the lack of plastic deformation of the highly cross‐linked epoxy network Copyright © 2003 Society of Chemical Industry     

反应性聚碳酸酯/环氧树脂体系的形态与增韧性能

将胺化聚碳酸酯（a-PC)和环氧树脂（EP)以一定的比例混合，加热到120－160℃后加入熔化的二氨基二苯基甲烷，可制备固化的胺化聚碳酸酯增韧环氧树脂，结果表明，EP与a-PC形成了网络结构，且当a-PC质量分数为10％时，试样断裂韧性最大。     

咪唑促进双氰胺固化环氧树脂体系固化动力学

采用差示扫描量热(DSC)法研究了2-乙基-4-甲基咪唑(2E4MI)的含量对双氰胺(DICY)固化环氧树脂体系固化动力学的影响。非等温DSC测试结果表明,2E4MI能大幅度降低DICY固化环氧树脂所需要的温度和活化能,从而加快反应的进行。当2E4MI用量为0.2份时,活化能最低为84.2 kJ/mol且整体活化能随固化度的变化较小、固化更均匀。在2E4MI最佳用量(0.2份)下对固化体系进行等温DSC以及潜伏性测试,结果表明,该体系在160℃下20 min内可完成固化,室温储存15 d的固化度仅为0.146,说明其适合用作快速固化环氧树脂储存体系。     

聚乙二醇接枝改性纳米炭黑对环氧树脂固化过程的影响

采用差示扫描量热法研究了以聚乙二醇(PEG)接枝改性的纳米炭黑(NC)(NC-PEG)为填料对环氧树脂/4,4-二氨基二苯砜非等温固化反应的影响,通过Flynn-Wall-Ozawa法和Malek法确定了固化反应的动力学参数.结果表明:两参数的自催化模型能够很好地描述环氧树脂及其复合材料的固化反应过程,各试样的模型拟合结果与实验数据相吻合.NC-PEG能够促进环氧树脂的固化,使固化活化能降低,其中,NC-PEG用量为3 phr时,活化能最低.     

Rheological Properties of Epoxy/Polypyrrole Coating and its Behavior as EMI Material

In this study, we analyze the rheological properties of epoxy/polypyrrole/carbon black coating and its performance as electromagnetic interference shielding efficiency (EMI SE). For this purpose, a commercial epoxy coating was mixed with a conductive polymer, namely polypyrrole. Rheological tests were performed to obtain the flow curve, the storage and loss moduli, the cure time and thixotropic characteristics. Thermal analysis of DSC (cure behavior) and EMI SE were also performed. Epoxy coating showed non‐Newtonian (shear thinning) behavior. The addition of PPy.DBSA reduced the coating fluidity by the increase in consistency index and viscosity. The stress oscillatory amplitude sweep test was performed to determine the linear viscoelastic range. The results of the LVR stress and strain frequency sweep tests were compared to the PPy.DBSA. The results show that LVR and critical crossover change with the percent of Polypyrrole. The cure times obtained by the rheometer and DSC were in good agreement: the addition of polypyrrole reduced the cure time, probably due to the presence of amino groups in the PPy.DBSA, which can react with the oxirane ring in the epoxy resin. The EMI SE attenuation by absorption and reflection mechanism was observed by adding 10 phr of PPy.DBSA. For practical applications, it is necessary to combine polypyrrole with conducting carbon black. The formulation with 1.5 phr of carbon black improves the EMI SE performance to 72%. J. VINYL ADDIT. TECHNOL., 26:348–353, 2020. © 2019 Society of Plastics Engineers